The Nokia Lumia 920 for AT&T started receiving the 1308 software update a couple of days ago which promised to bring improvements and enhancements to the handset, including a solution for the storage space reducing on Nokia devices. However it looks like it has made matters worse.Lumia 920 users began sharing various complaints on how they were having trouble maintaining a connection to AT&T. One owner explained how the connection would switch between LTE to EDGE to no service and then back again. Another owner's connection had been permanently switched to EDGE after the update.
The 1308 update added a new feature called Storage Check, which was designed to help empty the temporary cache files in the 'other' category. It turns out fixing the issue which caused Lumia devices to loose storage has opened up a new problem which Nokia now needs to fix.
Having a smartphone without proper network connectivity doesnt really keep it very smart, so users will be looking to Nokia for a quick response to this issue.
source - Reddit | WMPowerUser